Extremities Feature

Bone Healing During IM Lengthening: Clarity!

Elizabeth Hofheinz, M.P.H., M.Ed. • Tue, April 4th, 2017

Is that bone fully healed? Can the patient get up and walk around safely? Researchers from the Icahn School of Medicine at Mount Sinai in New York, who presented their results at the 2017 meeting of the American Academy of Orthopaedic Surgeons, set out to lessen the subjectivity of bone healing during lengthening.

Ettore Vulcano, M.D, assistant professor, orthopedics, Icahn School of Medicine at Mount Sinai. He commented to OTW, “During lengthening of a bone, the necessity for leg length discrepancies, new bone—called regenerate—is formed. This regenerate will mature over time to become solid bone. However, until this happens, the patient cannot walk to prevent fracturing at this site. To date, the assessment of bone healing has been subjective, based on the surgeon's experience. The aim of this study was to try to identify an objective means of assessing bone healing, regardless of surgeon experience.”

The authors wrote, “…the present study investigated bone regenerate pixel density on a picture archiving and communication systems (PACS) monitor after antegrade femur lengthening using IM [intramedullary] rods. Thirty-two consecutive patients who underwent antegrade femur lengthening using an IM rod at a minimum of 1-year follow up were included in this retrospective study…. Serial, 2-view radiographs of the femur were assessed by a single operator starting at the completion of lengthening (week 0). The pixel density of the lateral, medial, anterior, and posterior cortices was measured in each patient at every postoperative visit. These values were then compared to the adjacent 2 cm of bone just distal to the regenerate. The pixel density ratio (PDR) was calculated, and subsequently correlated to the subjective assessment of bone healing by one of the senior authors.”

Dr. Vulcano told OTW, “We were surprised to find an actual cut-off number that corresponds to good bone healing. Further analysis of the bone density measured with standard X-rays, demonstrated that the bone regenerate continues to mature and to get stronger even one year after surgery. As a matter of fact, it becomes even stronger that the native bone.”

“Having an objective measure of bone healing allows for comparison between patient visits. It allows a surgeon to say whether a bone is healed without looking at the X-rays (as long as a nurse, PA [physician assistant], resident, or colleague measures the bone density value—which requires minimal training). This is great if we consider patients that need to travel long distances to go to their orthopedist's office. It provides a more accurate and objective assessment of bone healing, translating into safer indications for patients in terms of when they can return to walk fully. In fact, premature weight bearing can lead to catastrophic failure of the rods used to lengthen the bones, whereas excessive non weight bearing can lead to osteoporosis, muscle atrophy, upper extremity pain (walking on crutches), blood clots.”

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Alternative Treatment Speeds Up Limb Lengthening

Biloine W. Young • Fri, July 24th, 2015

A specialized procedure that lengthens bones can also prevent amputations in selected patients who have suffered severe fractures, according to Loyola University Medical Center orthopedic surgeon Mitchell Bernstein, M.D.

Bernstein, is first author of a study, published in the journal Clinical Orthopaedics and Related Research. He reports that an alternative limb-lengthening technique makes the long recovery process less cumbersome, shortening it from 11 to 7 months. The story was reported by Newswise of Maywood, Illinois.

In standard limb-lengthening procedures, surgeons encase patients in a rigid frame made of steel and aluminum, called a “fixator.” The device contains three rings that surgeons place around the lower leg and secure them to the bone. This allows for manipulation of bone fragments with stainless steel pins.

Bernstein’s study examined an alternative technique that involved placing a titanium rod in the body in conjunction with the external fixer. Newswise reported that, “The alternative technique significantly reduced the amount of time patients had to spend in the external fixator.”

Limb lengthening works on the principle of distraction osteogenesis.

Four times a day, the external fixator pulls apart bone segments, and new bone tissue grows to fill the gap. Bone so treated lengthens at a rate of about 1mm. per day. According to Bernstein, bones can be lengthened by between 15% and 25% of their original length.

Once the new bone tissue is formed, it remains too fragile to bear any weight. It still takes several months for bone to fully regenerate. In the traditional bone-lengthening technique the patient stays in the external fixator until the bone is mature and strong enough to support the weight of the body.

In the alternative technique, the surgeon implants the titanium rod inside the bone to strengthen it and reduce the amount of time the patient must spend in the external fixator.

The Hospital for Special Surgery conducted the study. Fifty eight patients underwent limb lengthening. Thirty patients received the standard procedure and 28 received the alternative technique, which combined the external fixator with the titanium rod implantation. The average limb lengthening for both groups was 2.1 inches.

SC and PTH Increase Bone Formation, Speed Healing

Elizabeth Hofheinz, M.P.H., M.Ed. • Tue, December 15th, 2015

A group of researchers from Cedars-Sinai in Los Angeles is now closer to developing new treatments for patients with osteoporosis and spinal compression fractures. They found that using a combination of adult stem cells and parathyroid hormone (PTH) significantly increased new bone formation—and may speed healing for human bone fractures caused by osteoporosis.

As indicated in the December 8, 2015 news release, “For 21 days, laboratory rats and pigs with vertebral fractures received daily injections of PTH. During the same period, the animals also were injected with five doses of stem cells. The study shows that the combination therapy significantly enhanced the stem cells’ migration to the area of the bone fracture and increased the formation of new, healthy bone.”

“We have known that used separately, both the stem cells and the hormone each have an effect on the healing process involved in bone fractures, ” said Dan Gazit, D.M.D., Ph.D., co-director of the Skeletal Regeneration and Stem Cell Therapy Program in the Department of Surgery and Cedars-Sinai Board of Governors Regenerative Medicine Institute. “Now, we have learned that the stem cells and PTH are much stronger combined than they are separately.”

Said study co-author Zulma Gazit, Ph.D., co-director of the Skeletal Regeneration and Stem Cell Therapy Program, “Currently, there aren’t many good options for treatment. So our goal is to develop a biological treatment that not only promotes healing but also stimulates normal bone production.”

“We saw increased bone volume density and healthy bone formation only in the lab animals treated with both stem cells and hormone therapy, ” Zulma Gazit said. “Over the course of the study, we saw three-to-four times more healing in the groups that were treated with the combination.”

Gadi Pelled, Ph.D., assistant professor at the Skeletal Regeneration and Stem Cell Therapy Program and senior co-author of the study, told OTW, “The Gazit group has been studying the use of PTH for fracture repair for several years. One of the intriguing effects of PTH that we and others have noticed was that its administration led to endogenous stem cell recruitment and activation. Hence, we hypothesized that if we would ‘boost’ the number of circulating stem cells (mesenchymal stem cells in our case) combined with PTH administration, we would generate a synergistic effect that would accelerate fracture repair.”

“It is important to know that combining IV-injected mesenchymal stem cells and PTH yields a synergistic effect on fracture repair in osteoporotic animals.

Two Proteins Join Forces to Form Bone

Biloine W. Young • Tue, February 16th, 2016

If one bone-repairing protein does not work as you want it to—pair it with another. That is what researchers at UCLA did with the bone morphogenetic protein BMP2—an FDA approved bone healing protein. Unfortunately, the high doses of BMP2 that were required to induce human bone formation also caused swelling and inconsistent and inappropriate bone growth.

Now introduce the second protein NELL-1 which was discovered by Kang Ting, D.M.D., D.Med.Sc, professor and chair of the section of orthodontics at the UCLA School of Dentistry. When the two proteins are brought together there is increased bone formation. In addition, NELL-1 inhibited the formation of fat cells—a negative side effect of BMP2. The researchers found that NELL-1 encouraged stem cells to form bone cells instead of fat cells. Used together, the two proteins stimulate bone production more dramatically than either does alone.

“Before this study, large bone defects in patients were difficult to treat with BMP2 or other existing products available to surgeons, ” Ting said. “The combination of NELL-1 and BMP2 improved safety and efficacy of bone regeneration in animal models—and may, one day, offer patients significantly better bone healing.”

The study showed that NELL-1 works by activating the cellular signaling pathway that regulates whether a stem cell differentiates into a bone cell or a fat cell. It also showed that BMP2 can induce non-bone cells to form bone, with the potential risk for ectopic bone growth—bone formation in undesirable locations.

The researchers found that the two proteins complement each other. The BMP2 helps to turn non-bone cells into bone-forming cells, and NELL-1 increases the bone-forming ability of bone cells. One of the investigators, Chia Soo, M.D., professor of plastic surgery and vice chair for research at the David Geffen School of Medicine at UCLA, said, “ In contrast to BMP2, the novel ability of NELL-1 to stimulate bone growth and repress the formation of fat may highlight new treatment approaches for osteoporosis and other therapies for bone loss.”

The study will appear as the lead article in the February edition of the American Journal of Pathology.

New Limb-Lengthening Surgery Performed

Biloine W. Young • Tue, March 4th, 2014

Two Baltimore surgeons have performed the first surgery in North America using the P2—the latest generation of Ellipse Technologies, Inc.’s Precice Limb Lengthening System. John Herzenberg, M.D., the director of the Rubin Institute’s International Center for Limb Lengthening (ICLL) and Shawn Standard, M.D., head of Pediatric Orthopedics at the ICLL, inserted the P2 rod into the tibia of a patient at Sinai Hospital earlier this year.

According to a report by LifeBridge Health, the Precice Limb Lengthening System was the first externally controllable internal limb lengthening system to receive clearance by the FDA. The system was co-developed by Standard and Herzenberg in collaboration with Ellipse Technologies of Irvine, California, and Stuart Green, M.D., clinical professor of orthopedic surgery, University of California, Irvine. Launched in early 2012, the first generation of the Precice was the first fully controllable internal limb lengthening system available to medical professionals.

“The Precice Limb Lengthening System represented a revolutionary advancement in the field of limb lengthening, ” said Herzenberg. “This introduction of the P2 is the next step in this ongoing evolution. The Precice system has been a great success at the Rubin Institute. Since 2012, the ICLL has performed 100 surgeries using the initial Precice. We expect similar results with the new P2, along with expanded applicability to younger and smaller patients, because the P2 nail is available in a smaller size (8.5 mm diameter) compared to the original Precice nail.”

The Precice Limb Lengthening System uses a telescopic titanium rod surgically implanted in either the femur or tibia in conjunction with an external remote controller to internally lengthen bones in the leg. Inside the rod, a miniature magnetic motor and gear box create the force needed to lengthen the rod. The power to drive the internal motor is supplied by a magnetic field generator that is held on the skin next to the leg several times a day for a few minutes.

Limb lengthening is used to treat upper and lower limb length deformities. Ellipse officials explain that through this process, new bone and soft tissues are gradually grown. The new growth is called distraction osteogenesis.

Engineers Tackle Rotator Cuff Repair

Biloine W. Young • Tue, March 25th, 2014

Rotator cuff tears are among the most common orthopedic injuries suffered by adults in the United States, according to a report in Medical Press. The culprit? Wear and tear and the effects of age.

Using a five-year $3.1 million grant from the National Institutes of Health (NIH) researchers in orthopedics have joined together with engineers at Washington University, St. Louis, Missouri, to study the way tendons attach to bones. They believe that further understanding of this connection could lead to the engineering of new tissues to enhance cuff repair.

Medical Press quoted Guy Genin, Ph.D, professor of mechanical engineering, as saying, "Every motion you make is related to the attachment of tendon to bone. The muscle is attached to the tendon, and the tendon is attached to the bone. Any break in the linkage will prevent motion, so this attachment is vital to the way the body works."

Four tendons connect the large arm bone muscles to the shoulder. Surgeons repair tears in the cuff by suturing the tendon directly to the bone. This does not always work well. "The natural attachment system is not regenerated during healing, even following surgical repair, " noted Stavros Thomopoulos, Ph.D., associate professor of orthopedic surgery in the School of Medicine. "The healing process leads to scar-tissue formation at the tendon-to-bone interface, and the resulting attachment is prone to re-injury."

The two men are leading an interdisciplinary group that is trying to better understand the tendon-to-bone attachment and figure out what goes wrong in the healing process following surgery. "When material is structured like tendon and bone, mechanisms for smooth attachment and transfer of stress are harder to design, " Genin told Medical Press. "Nature has a great design and surgical repair techniques might be improved by better understanding this. We need engineering approaches to determine what's important.”